a. Field of the Invention
The present invention relates generally to solid state laser rods, and more particularly to flashlamp pumping of solid state laser rods.
b. Description of Related Art
Solid state lasers are those in which the gain medium is a solid material usually having the form of an elongated cylindrical rod. Typically, the rod is composed of crystalline material, a glass or a plastic doped with an active ion such as Nd.sup.3+ or Cr.sup.3+, which provides lasing action in a laser resonator defined by a pair of mirrors. In such lasers, the solid state laser rod reaches an active state ready to provide laser gain upon exposure to the light from a flashlamp. The light from the flashlamp is directed to the laser rod by a reflector. Applications of such solid state lasers include medical, machining and military uses. Solid state lasers are advantageous in that they are compact, reliable for long term use and easily replaced in the field.
Two types of pump chamber reflectors have dominated laser designs--reflectors that are specular in nature and those that are diffuse. Typical specular pump chambers are made of highly polished surfaces that are coated to enhance the reflectivity of the pump light. Specular reflectors are generally well defined shapes and provide high light transfer efficiency but less uniformity of gain distribution. Therefore, flashlamp pumping of the laser rod gain media can create localized high gain areas when using specular reflectors.
Typical diffuse pump chamber reflectors are made from ceramics and require that the pump chamber be very compact since it is a non-imaging system. The transfer efficiency of the energy from the flashlamp to the laser media is highly dependent on the cross-sectional area of the pump chamber in relation to the cross-sectional area of the laser media. The transfer efficiency of a pump chamber also depends on the number of reflections off the reflective surfaces and the loss incurred at each reflection. The uniformity is generally very high since the laser media is bathed in a nearly homogeneous pump light field. Diffuse pump chambers generally have a higher uniformity of gain distribution but a lower efficiency than specular pump chambers.